Third seed Alexandrova claimed a comfortable 6-1 7-5 win in 80 minutes to setup a meeting with Clara Burel, who clinched a surprise 6-3 6-1 win over Varvara Gracheva despite being ranked 56 places below her opponent.
Kristyna Pliskova was knocked out following a hard-fought 7-5 6-4 loss to Alize Cornet.
Cornet's reward is a tie with eighth seed Magda Linette, who triumphed 6-2 6-0 in a one-sided match against Nao Hibino.
Both Bencic and Kasatkina did not have to play a semi-final after their respective opponents, Veronika Kudermetova and Paula Badosa, both pulled out with injuries.
Bencic romped to victory in the final though, dropping just two games against her Russian opponent to lift her first title in Australia.
The match lasted just 67 minutes, as the 2021 runner-up converted five of her seven break point opportunities while not facing a single break point herself.
Bencic rattled off eight games in a row to start the final, and though Kasatkina did save some face with a couple of holds late on, the world number 13 finished the job to win in straight sets ahead of the start of the Australian Open next week.
"I'm happy I could show my work here on the court," Bencic told reporters at a post-match news conference. "I thought I played some great matches from the start of the tournament and also against different kind of opponents so I really could test myself out there in every way and just go confidently into the Australian Open."
At the Hobart International, Lauren Davis ended a six-year title drought with a 7-6 (7-0) 6-2 triumph over Elisabetta Cocciaretto in an all-unseeded final.
In the opening set, every game went to serve until the tie-break, when Davis found three crucial breaks to take the advantage heading into the second stanza.
But the second set was not the same tight affair as Cocciaretto, playing in her first Tour-level singles final, collapsed to a 5-0 deficit to leave her staring down the barrel of defeat.
Davis, who herself was playing in a first Tour-level final since winning the trophy in Auckland in 2017, overcame losing the next two games to take the title having not lost a set at the tournament.
Davis was delighted after the match, saying: "I have a lot of emotions going through my body right now. I'm just really happy, really excited. I really had to play my best in order to win today."
Back after more than seven years off the WTA Tour, Clijsters fell to a second straight loss, going down to second seed Johanna Konta 6-3 7-5 in the first round.
Clijsters, a wildcard at the WTA International tournament, managed to win just 12 return points in the 85-minute loss as Konta posted her first win of the year.
The four-time grand slam champion has been handed two tough draws this year, having lost to Garbine Muguruza in Dubai last month.
Playing for the first time since last year's US Open, seventh seed and last year's runner-up Azarenka was beaten 6-2 6-2 by Tamara Zidansek.
Top seed Elina Svitolina cruised through the opening round with a 6-3 6-2 victory over Danka Kovinic.
American 10th seed Lauren Davis also eased through, while there were wins for Anastasia Potapova, Leylah Fernandez, Arantxa Rus, Kateryna Bondarenko and Tatjana Maria.
The 2021 US Open champion made a winning return to the court at the ASB Classic in Auckland on Tuesday after being sidelined since April following operations on both her wrists and one ankle.
It appeared that Raducanu was going to be required to go through qualifying for the Australian Open due to her protected ranking – given to players who have been sidelined long term – not being high enough.
However, the Australian Open announced in a post on X, formerly Twitter, on Wednesday that the 21-year-old would take the place of American Lauren Davis in the main draw after the American withdrew due to a shoulder injury.
Davis joins French Open finalist Karolina Muchova, Irina-Camelia Begu and Caty McNally on the withdrawal list.
Two-time Wimbledon champion Petra Kvitova has also withdrawn from the tournament after announcing she is pregnant with her first child.
Seeded ninth for the WTA International tournament, Japan's Hibino was upstaged 3-6 6-2 6-3 by Jasmine Paolini on Monday.
American eighth seed Li, however, had no such trouble in her 6-3 7-5 victory over Arantxa Rus on the outdoor hard courts.
Coco Vandeweghe – the 2017 Australian Open semi-finalist – suffered another early exit in Mexico.
After being ousted by Mihaela Buzarnescu in the opening round in Guadalajara last week, former world number nine Vandeweghe was eliminated 6-3 6-2 by Canadian teenager Leylah Fernandez.
Fernandez will face either top seed Sloane Stephens or lucky loser Kristina Kucova in the second round.
Anna Karolina Schmiedlova, Nina Stojanovic, Viktoria Kuzmova, Lauren Davis and Tamara Zidansek also progressed from the opening round.
The world number 26, who was defeated by Amanda Anisimova in the Melbourne Summer Set 2 semi-finals last week, beat second seed Muguruza 6-4 6-4.
Kasatkina held throughout the opening set, landing 67 per cent of her first serves, and saw the job through in the second despite a couple of early breaks for Muguruza.
It is the Russian's first win over a top-five opponent since beating Caroline Wozniacki at the 2018 French Open.
She will now face fifth seed Paula Badosa, who saw off Olympic gold medallist Belinda Bencic 7-6 (8-6) 3-6 6-3 in an entertaining match lasting two hours and 35 minutes.
The other semi-final in Sydney will be contested between Anett Kontaveit and Barbora Krejcikova, who advanced past Ons Jabeur and Caroline Garcia respectively.
Krejcikova proved far too strong for Garcia, prevailing 6-0 6-2 in 70 minutes, while Kontaveit was in action for just 43 minutes before being handed a walkover win in her match.
Jabeur had targeted "payback" against Kontaveit after her quarter-final opponent pipped her to the final WTA Finals spot in November, but injury cost her the chance to do so.
Having lost the first set 6-4, Jabeur – who eliminated Petra Kvitova in the previous round – felt unable to continue due to a lower back injury.
At the Adelaide International 2, three of the five Americans in action made it through to the semi-finals.
Alison Riske's clash with compatriot Madison Brengle ended early due to the latter retiring with the first set level at 3-3. Tamara Zidansek awaits Riske after beating Lauren Davis 7-6 (7-4) 7-6 (9-7).
Coco Gauff and Madison Keys will meet in the other semi-final, meanwhile, following victories over Ana Konjuh and Ludmilla Samsonova in two and three sets respectively.
The 26-year-old won five out of the final six games as she stormed to the first set, before securing her place in the quarter-finals with a superb second set in which she broke Martincova four times.
Fellow Estonian Kaia Kanepi is also through to the quarter-finals after a 7-5 7-5 victory over Ann Li.
The world number 32 found a crucial break with the opener tied at 5-5 as she took the first set, before breaking Li three times in the second to seal the win.
Eighth seed Shuai Zhang was dumped out by Donna Vekic in a 6-2 6-4 defeat, while fellow seed Jil Teichmann also saw her tournament ended as Ysaline Bonaventure beat her 7-6 (10-8) 6-3.
At the Parma Ladies Open, top seed Maria Sakkari came from a set down for the second consecutive match to overcome Maryna Zanevska and reach the semi-finals.
Zanevska sparked hopes for an upset as she broke the world number seven three times on her way to taking the opening set.
But Sakkari improved in the second to tie the match, before overcoming two breaks of serve from her Belgian opponent to win six of the last seven games and earn a 2-6 6-4 6-4 success.
Sakkari will face Danka Kovinic in the semi-finals, after the 27-year-old's 6-4 6-4 triumph over Italian Jasmine Paolini.
Irina-Camelia Begu's run of 12 consecutive wins on clay came to an end as she was defeated 6-2 7-6 (8-6) by Ana Bogdan in an all-Romanian clash.
Bogdan's opponent in the final four will be Mayar Sherif, who beat American Lauren Davis 7-6 (7-2) 6-3.
Sixth seed Kudermetova showed great defiance to defeat American Collins 4-6 7-6 (7-5) 6-1 on Thursday.
Kudermetova fended off five match points when serving to stay in the tournament at 6-5 down in the second set and duly forced a tie-break.
Collins, runner-up to Ash Barty in the Australian Open final last year, took a 3-0 lead in the breaker, but back came her Russian opponent to level the match.
The world number nine dominated the deciding set to seal a meeting with Bencic in the last four.
Eighth seed Bencic got the better of WTA Finals champion Garcia 6-2 3-6 6-4.
Garcia broke straight back after going 3-1 down in the final set, but Bencic broke for the fourth time in the match to go through.
Paula Badosa and Daria Kasatkina will contest the other semi-final after beating Beatriz Haddad Maia and Petra Kvitova respectively.
Elisabetta Cocciaretto saved two match points as she came from a set down to beat Bernarda Pera 5-7 7-6 (10-8) 6-4 in the quarter-finals of the Hobart International.
The 21-year-old Italian will now face 2020 Australian Open champion Sofia Kenin, who also stormed back to defeat Anhelina Kalinina 4-6 6-3 6-1.
Lauren Davis and Anna Blinkova will do battle in the other semi-final following wins over Wang Xinyu and Yulia Putintseva respectively.
Two-time Wimbledon winner Kvitova hit 21 winners to 12 unforced errors on her way to a 6-3 7-5 win against reigning SW19 champion Rybakina in a match lasting 87 minutes.
Belinda Bencic, a defeated finalist in this tournament in 2021, also advanced with a 6-3 6-4 win against former world number one Garbine Muguruza to maintain her positive form.
Fellow seeded players Beatriz Haddad Maia and Danielle Collins beat Sorana Cirstea and Karolina Pliskova respectively to book their places in the last 16.
At the Hobart International, favourite Marie Bouzkova saw off Jacqueline Cristian 7-6 (7-2) 6-3, while Lauren Davis defeated Sloane Stephens 6-2 6-2 in an all-American clash.
Following her third-round appearance at the Volvo Car Open, Charleston native Rogers moved through to the quarters of her second hometown tournament in as many weeks after easing past qualifier Claire Liu 6-2 6-2.
"I think I was due for a couple of tame matches," said third seed Rogers, who lost to world number one Ash Barty at last week's Volvo Car Open. "I've had quite a few mental battles over the last couple of months, so it's been nice to just take care of business in straight sets, get in and get out."
Next up for Rogers at the WTA 250 event is in-form Montenegrin opponent Danka Kovinic, who upstaged seventh seed Davis 6-1 1-6 6-3 on Wednesday.
Australian sixth seed Tomljanovic was swept aside by teenager Clara Tauson 6-1 6-4, while Nao Hibino beat Francesca Di Lorenzo 6-4 6-3.
The number two seed won 7-6 (10-8) 7-6 (7-3), saving seven set points after going 5-1 down in the first set, before roaring back to take both tie-breaks.
Sabalenka will face Marketa Vondrousova in the quarter-finals, with the Czech having produced a dominant performance in a 6-0 6-4 win against Kaia Kanepi.
"When it's 1-5 down, it's like you have nothing to lose, and you just go for your shots without thinking," Sabalenka said.
"That really helped me to stay in the set, to keep fighting and to keep trying."
Fourth seed Veronika Kudermetova eased through after a 6-4 6-0 victory against Bianca Andreescu, while Marta Kostyuk also advanced with a hard-fought 6-7 (5-7) 6-2 6-3 win over Elena Rybakina.
At the ASB Classic in Auckland, second seed Sloane Stephens is out after falling to Rebeka Masarova.
Having been forced to resume on Wednesday after rain suspended play the previous day, Stephens struggled against her Spanish opponent, eventually losing 6-3 7-6 (7-5).
Fifth seed Wang Xiyu is also out after retiring from her match against Karolina Muchova, but seventh seed Danka Kovinic is through after a simple 6-1 6-4 win against Nao Hibino.
Kovinic will face Lauren Davis next after she overcame Tamara Zidansek 6-2 6-1, while fellow American Sofia Kenin will take on number one seed Coco Gauff in the last 16 after she beat Wang Xinyu in straight sets.
Svitolina, the top seed at the WTA International event, was too strong for Belarusian Olga Govortsova 6-3 6-4 in one hour, 18 minutes.
The Ukrainian managed four breaks of serve in her victory, moving into a last-eight clash with Canadian teenager Leylah Fernandez.
Konta was pushed more but still got past German Tatjana Maria 7-6 (7-4) 6-3.
The British second seed was wasteful, converting just one of 12 break points to advance.
Russian Anastasia Potapova awaits in the quarter-finals after overcoming Tamara Zidansek 1-6 7-6 (7-3) 6-1.
Arantxa Rus also booked a spot in the last eight thanks to a 7-5 6-0 victory over American 10th seed Lauren Davis.
The two-time French Open champion, who enjoyed a 37-match winning streak earlier this year, defeated Davis 6-3 6-4 in one hour and 57 minutes.
Swiatek had trailed 3-0 in the second lap but fought back emphatically to seal her passage into the last 16 where she will face either Jule Niemeier or Zheng Qinwen.
The attention in the women's singles has firmly turned to Swiatek, with Serena Williams eliminated along with the second, third and fourth seeds.
The Pole did not disappoint, hitting 25 winners and six aces, albeit with 38 unforced errors and an apparent lack of rhythm.
Swiatek wrapped up the first set in 59 minutes but world number 105 Davis offered a tougher test in the second after breaking in the second game.
The highly favoured Swiatek had to work out to avoid a 4-0 deficit, holding her serve in a 16-point game, but she showed she was back breaking Davis to love to make it 3-4.
Swiatek won 21 of the last 25 points of the match to book her spot in the second week in New York for the second straight year.
Data Slam: Swiatek finding her hard-court groove
The win improved Swiatek's 2022 tally to 53 matches but it also moved her a step closer to becoming the first player since Serena Williams in 2014 to win seven titles in a single year.
Swiatek has not quite reached the same dizzying levels lately since her 37-match winning streak, which was halted in the third round at Wimbledon, with this victory being only her fifth from eight during the hard-court season.
WINNERS/UNFORCED ERRORS
Swiatek – 25/38
Davis – 12/34
ACES/DOUBLE FAULTS
Swiatek – 6/3
Davis – 0/6
BREAK POINTS WON
Swiatek – 3/14
Davis – 1/3
Swiatek reached the second week at the US Open for only the second time after Saturday's 6-3 6-4 win over Lauren Davis and has moved into title favouritism, creating a level of perceived pressure.
That comes amid a run of form where the 2020 and 2022 French Open champion has been far from the levels achieved during her 37-match winning streak which ended in July at the hands of Alize Cornet at Wimbledon.
Since then, Swiatek has only won seven of 10 matches. Swiatek's victory over Davis marked the first time since the winning streak that she has managed three straight victories.
The Pole's hard-court form line has not been compelling either but the exit of Serena Williams along with top seeds Anett Kontaveit, Maria Sakkari, Paula Badosa and Simona Halep has thrust her into US Open favouritism.
But the 21-year-old is trying not to put any extra pressure on herself with that in mind, nor re-discovering the form she displayed earlier in the year.
"Honestly I didn't even focus on that cause I still remember how it is to lose," Swiatek told reporters. "After the tournament in Cincinnati [when she lost to Madison Keys in August], I knew like it's not the end of the world that I'm losing in third round.
"It's not like the whole universe changed so right now I'm always going to be in quarter-finals or finals or whatever, win tournaments. I tried just to remind myself that it's kind of normal, that it's impossible to play always on the same level.
"Here I just took it match by match. I wasn't expecting maybe too much because of the losses, so that's good. It's not like I lost confidence or something. I still know anything can happen on these tournaments."
Swiatek admitted she lacked rhythm against Davis, who had led 4-1 in the second set, before the Pole fought back to win the final five games.
The 21-year-old won 21 of the final 25 points of the match, securing her 53rd victory of the 2022 season, closing in on Ash Barty's 57 from 2019.
"It wasn't as smooth as in first and second round," Swiatek said. "I'm pretty happy I made it through and could close it in second set and come back. That was pretty important for me.
"For sure she played totally differently than most of the players, which threw me a little bit off the rhythm. But I'm happy I was fighting till the end."